1. Field of the Invention
The present invention relates to a process for upgrading an absorbent hydrocarbonaceous oil containing contaminants such as sulfur or nitrogen.
2. Description of the Prior Art
In fractionation processes in which sulfur and/or nitrogen-containing hydrocarbonaceous oils are separated into fractions having different boiling points, it is known to introduce an absorbent oil into an absorption zone of the fractionator to contact the upflowing vapors of the feed to be separated and thereby remove at least a portion of the contaminants from the upflowing vapors by absorption in the absorbent oil, which is commonly known as wash oil. The absorption zone is typically positioned in the intermediate portion of the fractionator below the withdrawal pan of the lowest distilled sidestream product and above the flash zone into which the heated liquid and vapors are introduced into the fractionator. After performing its washing function in the intermediate section of the fractionator, the contaminated absorbent oil stream flows down through the flash zone into the fractionator bottoms product or it may be withdrawn by installation of a suitable withdrawal pan from the fractionator as a separate stream. When the absorbent oil is permitted to mix with the bottoms product, it becomes part of a lower value porduct. When the absorbent oil is withdrawn as a separate (i.e., discrete) stream, the contaminated absorbent oil has a low value since it is contaminated with the undesirable materials that are absorbed from the contaminated vapor stream that it had washed.
U.S. Pat. No. 2,472,810 discloses withdrawing a wash oil from a fractionator and passing it to a wash oil purifier. In the purifier, the wash oil is vaporized by steam from its non-volatile impurities. The purified wash oil is returned as a vapor to the fractionator.
U.S. Pat. No. 2,913,374 discloses withdrawing a wash oil from a stripping tower to a purifier. Stripping steam volatilizes the wash oil from a residue. The purified wash oil is returned to a stripping tower.
U.S. Pat. No. 2,922,751 discloses purifying a wash oil from a stripping tower in a purifier by steam volatilizing wash oil from the impurities. The purified wash oil is returned to the stripping tower.
U.S. Pat. No. 2,927,061 discloses purifying a rich absorption oil in a purifier by heating and then sending the vaporized rich oil to a still.
It has now been found that a contaminated absorbent oil can be upgraded by a hydrorefining process.